The present invention relates to a slip-controlled brake system.
A similar brake system is described in German published patent application No. P 36 27 000. The principle function of the brake system therein is as follows: when brake slip control commences, pumps are driven by a motor, and delivered pressure fluid is fed into the working chambers of a master cylinder. As a result, the pistons of the master cylinder and, thus, the brake pedal are returned to their initial positions. As soon as this initial position is reached, the central valves in the master cylinder open until a throttling position is reached so that just enough pressure fluid discharges from the working chambers into the supply reservoir as is required in order to generate pressure in the working chambers that is proportional to the pedal force. Accordingly, the wheel brakes are supplied with pressure fluid from the pump during a slip action that is under pressure proportional to pedal force.
The prior system has the disadvantage that the pedal is returned to its initial position (which is the brake's release position) upon commencement of a slip control action. Some drivers sense this to be unpleasant particularly when braking is performed at a high frictional value in which case the pedal is depressed far down and has to cover the entire actuating travel when resetting.